Control for hydraulic transmissions.



W. FE'R'RIS & W. E. MAGIE.

coNTRoL FoR HYDRAULIC TANsMlssIoNs.

APPLICATION FILED )UNE I4, I9I5.

3,59,9@ www Mar. 12, 1918.

`TEE STATES PATENT @FFEO WALTER EERRIs, 0E MILWAUKEE, WIsooNsIN, ANDWILLIAM E. MAGIE, or

EvANsvILLE, INDIANA. y

GDNTROL FOR HYDRAULIC TRANSMISSIONS.

naaaoao.

To all whom t may concern:

Be it known that we, WALTER FERRIS and WILLIAM E. MAGIE, citizens of theUnited States, residing, respectively, at Milwaukee, in the county ofMilwaukee and State of Wisconsin. and at Evansville, in the county ofVanderburg and State vofflndiana, have invented a certain new and usefulImprovement in Controls for Hydraulic Transmissions, of which thefollowing is a specificat1on.

Our invention relates to improvements in control means for hydraulictransmission and has for one object to provide a means for automaticallycontrolling the transmission itself and the prime mover which operatesit. 1For the purpose of convenience we have selected an ordinary gasengine as the prime mover and the transmission we have illustrated as apump wherein the stroke may be varied for the purpose of changing theout-put per revolution. The liquid pumped by this pump operates a motor`which motor in turn carries the load or overcomes the resistance. Thepower requirement may be met by various reciprocal combinations of pumpspeed with-pump displacement. -For instance, if the pumps maximumcapacity is 100 cubic inches displacement per revolution and 1000revolutions per minute and 500 pounds per square inch pressure, the pumpwill deliver about 125 H. P. when all these Variables are maxima.Suppose now that the resistance consists of a torque in the motor shaftof 4000 inch lbs. at 500 revolutions per minute yor about 82 H. P. Thisrequires that 500 (revolutions per minute of motor) -l- 100 (cubic inchdisplacement of motor pistons er revolution) equals 50,000 cubic inchesof oil be handled by the pump in one minute; also that this oil bepumped into the motor at 250 lbs. pressureas the required torque of 4000inch lbs. is one-half of the maximum torque; maximum equals 100 cubicinches 500 lbs. per sq. in. pressure divided by 6.2832 equals A8,000inch lbs.

Now the pump can handle 50,000 cubic inches of oil per minute at 250lbs. pressure vin an infinite number of ways and still meet therequirementthat the motorbe drivenv at Specification of Letters Patent.

- 500 revolutions per minute. Thus the pump Full stroke ..-and 5400revolutions per minute las L d H l H LL :1U H and LI H i 196 u and u u ne, "Zand 1000 f and 1 250 ,au v and 1666 itself to give the torquerequired by the resistance. This, however, will not be an economicalmethod because during light torques and small speeds of motor both prlmemover and pump will be running at high speeds and small torque, whileboth of them would have a better efliciency at lower speeds and highertorques. ln the above case, it will be better to have the pump runningat full stroke and 500 revolutions per minute, thus slowing the gasoleneengine down to V500 revolutions. Even at this speed it only gets anindicator card of one-half of full load area, as the torque delivered bythe motor is one-half full load torque. The transmission also will workat higher eicienoy with full stroke and slower speed.

The object of the mutual control, therefore, is to obtain a highereiiciency for the combined prime mover and transmission pump at smallpower deliveries by reducing their speeds as permitting them to delivera high enough torque to run at good eiiciency despite the reduced load.

This mutual control may be worked out in a great many forms. ln theaccompanying drawing we show a form in which the operator selects theposition of the lever or other control means to ix the pumpdisplacement,

Patented Mar. 12, i918.

Application led June 14, 1915. Serial No. 33,920.

-closely connected one to the other.

pump housing contains the variable dis-- the secondary automatic devicescontrolling the speed and torque of the prime mover corresponding to thework done by the pump and hydraulic motor. The invention is illustrateddiagrammatically in the accompanying drawing, wherein is shown a sideelevation.

A is a prime mover which we have here shown for convenience as anysuitable wellknown type of gasy or other internal combustion engine. A1is a centrifugal governor driven by any suitable mechanism as shown fromthe engine crank or drive shaft A2. A3 is a carbureter adapted to supplya combustible fluid to the yair drawn in through the intake pipe A4controlled by the throttle valve A5. The carbureter discharges thecombustible mixture thus formed to the engine and theengine thenoperates in the usual manner being controlled in its speed and powerout-put by the throttle valve.

B is a pump housing. B1 a motor housling charge pump not hereillustrated adapted to be driven at all times in unison with the primemover by the drive shaft A2 which extends from the prime mover to thepump. The ump is connected to the motor by any .suita le hydraulictransmission pipes not here shown. B2 is a motor shaft driven by andadapted to be driven at all times with the motor. It carries a pinion B8in mesh with a gear B4 which gear'in turn is connected to the resistanceor load which it is" proposed to move.

C is a pump control lever. When it is in the neutral position the pumpwhile still rotating with the prime moverdoes not have any discharge anddoes not therefore do any useful work. Therefore, while the lever is inthe neutral position the motor is at rest. When the lever is moved tothe right the pump forces the fluid in one direction through the systemand when moved to the left the fluid is discharged in the oppositedirection and thus causes the motor toturn in one direction or the otheras the case may be. e The farther the lever is moved from neutral towardits extreme position the greater the iow of the pump and therefore thegreater the amount of Huid displaced and the higher the speed of themotor. C1 `is an arm projecting from the control lever C carrying a cammember C2. C3 is a link slidable in the :bearing C4 on a housing Bhaving a roller C in engagement with the cam member C2 and pivotallysupporting at its free end a floating lever C". This floating lever .iscon- `nected by a link C1 to a bell crank lever Cs controlled by thegovernor A1.

Intermediate the two -ends of the floating lever C is a lug D. This lugD has pivotally connected thereto one end of a pressure control floatinglever D1, the pivot pass- D7 tends to move the piston and rod to theright and hydraulic pressure from the transmission system with which thecylinder D6 is connected by the pipe D8 tends to resist this movement ofthe piston and forces .it to the left.

It will be evident that while we have shown in our drawings an operativedevice, still many changes might be made both in size, shape andarrangement of parts without departing from the spirit of ourvinvention,and we wish, therefore, that the drawings be regarded as in a sensediagrammatic.

The pressure cylinder and piston and cooperating parts form what is ineffect a hydraulic governor which operates responsive to the pressure inthe pump and circulating system.

The use and operation of our invention is as follows In the neutralposition of lever, as shown, the pump has no displacement, there istherefore no pressure in the system and the cylinder and theprime moveris operating only at friction load. The centrifugal governor is set fora suicient throttle opening to maintain a low engine speed, say halfspeed, at friction load. `As the hand lever is moved in eitherdirection, giving a displacement to the pump, the cam surface, link andoating levers give additional opening to the throttle, enabling theengine to meet the increased load which is to be anticipated as a resultof the increased displacement. Should the torque encountered by thehydraulic motor also increase, the pressure in the pump will increaseproportionately. Should this occur, the hydraulic cylinder D6 andco-acting parts also give corresponding additionalopening to thethrottle independently of the opening resulting from increasing thedisplacement of the pump. Both "increments of' throttle opening aresuicient operator, and the higher the pressure in the pump cylinderswhich results from the resistance encountered by the hydraulic motor. The centrifugal governor attached to the prime mover checks at a properpredetermined point the increases of speed due to the additionalthrottle opening accompanying the increases of displacement andpressure..

Thus the prime mover will always tend to work at the maximum practicabletorque and the lowest practicable speed for a required power output.

In this arrangement the judgment of the operator is relied upon toselect a displacement within the power capacity of the enine. Otherautomatic devices may readily e introduced to protect the engine fromoverload.

Thus there are three controls all of them operating upon the throttle.lf the governor speeds up with nothing else moving it tends to close thethrottle. Tf the rotation of the prime mover increases the pump willwork harder and the pressure will rise. This will thrust the piston outand open the throttle.. Tf the hand lever is moved to increase thestroke of the pump this will open the throttle. ny two of thesemovements may occur simultaneouslyor any three of them and it is thesummation of the two or three movements as the case may be whichcontrols the speed and torque of the engine.

Tt will be understood that the power out-.

put of the prime mover is controlled by manipulation of the throttlevalve and that this manipulation or operation of the throttle valve is a'summation of the control movements resultant upon the action of theinertia governor driven by the prime mover, the hydraulic governoroperated by the pressure on the pump and the control lever which adjuststhe displacement of the pump irrespective of its rotational speed. Thusvelocity changes in the prime mover and pressure changes in the pumpsystem and the manual manipulation of the displacement of the pump allthree in unison affect the throttle and thus the power output of theprime mover, Tf any two of these different forces are inactive the otherforce will directly control the power output. Tf any two or more ofthese forces are simultaneously active the power output control will bethe resultant of the simultaneous action of these separate correlatedcontrolling movements.

This arrangement is shown applied to the throttle of a combustion motor.Tt might be equally well shown applied to a control memher for any typeof prime mover, for instance, the throttle valve of a steam engine, therheostat control of an electric motor or any other suitable arrangementof prime mover and control.

The pump that we have shown is a pump having a rotating part and thatrotating part is the controlling and driving part and, therefore, thespeed of the pump may be and we have preferably expressed it in terms ofrotation, though it is perfectly obvious that it might be expressed inother terms, as for instance, terms of reciprocation or in terms ofcomplete cycles of operation. lt is possible toconceive of a pump inwhich there is no rotating part but there must be some kind of arotating connection and any reciprocatory movement of the pump and theprime mover whether mechanically translated into rotary movement or notcan be expressed in terms of rotation. Therefore, we do not wish ourinvention to be considered as limited to a pump or a prime mover whichrotates as there are, of course, reciprocating parts as we have shownand there might be reciprocating parts without rotary parts, though thepreferred forms is as we have indicated. f

Generally speaking, our device is intended to be used with threeelementsfof control, viz: the centrifugal governor, vthe hydrauliccylinder governor and the hand lever. Tt is, of course, perfectlyobvious that any one of the three may be rendered inoperative ordispensed with without impairing the util- 'ity of the'invention. Forinstance, if the operation of the hydraulic governor should be arrested,the hand lever and the centrifugal governor only will be in operationwhereupon the mechanism will act as follows:

As the operator increases the displacement of the pump by moving thehand lever, the throttle opening of the prime mover is automaticallyincreased to take care of anticipated larger load. This larger loadwill, of course, comprise elements of larger displacement and higherpressure in the pump. rThe latter' element is now not included in theautomatic control and the result will be that the centrifugal governoron the engine will effect the necessary throttle opening by lowering thespeed of the engine until it is able to take care of the increasedtorque. Tf the engine runs too slowly or threatens to shut down, theoperat-or merely moves the hand lever reducing the displacement,permitting the engine to run at higher speed and less torque.

Similarly the control elements might comprise only the centrifugalgovernor and a pressure cylinder in connection with a pump whosedisplacement is not varied. The operator would then vary the pressure inthe pump by increasing` or decreasing the resistance of the hydraulicmotor.

We claim l. A prime mover, a pump driven thereby, a motor driven by thepump, means for varying the displacement of the pump independent of itsrate of rotation andy means responsive to the rotational speed of theprime mover, the pressure inthe pump and the displacement varying meansfor controlling the power, output of the prime mover. 2. A prime mover,a pump driven thereby, a motor driven by the pump, means for varying thedisplacement of the pump independent of its rate of rotation, means forcontrolling the power output of the prime mover and separate actuatingmembers for said means responsive to the speed of rotation of the primemover, the pressure inthe pump and the displacement varying means.

3. A prime mover, a pump driven thereby, a motor driven bythe pump,means for varying the displacement of the pump independent of its rateof rotation, means for controlling the power\output of the prime moverand separate actuating members for said means responsive to the speed ofrotation of the prime mover, the pressure in the pump and thedisplacement varying means, said operating members being interconnectedand mutually interdependent in theirtotal effect upon the power control.j

4. A prime mover, a pump driven thereby, a motor driven by the pump,means'for varyin the displacement of the pump Yindepen ent of its rateof rotation, an inertia governor driven by the prime mover, a hydraulicgovernor operated by the pressure in the pump, means for controlling thef power output of the prime mover, separate control.

operative connections between the power control and the two governorsand the displacement control. 5

5. A prime mover, a pump driven thereby, a motor driven bythe pump,means for varying the displacement of the pump independent of its rateof rotation, an inertia governor driven by the prime mover, a hydraulicgovernor operated by the pressure in the pump, means for controlling thepower output of the prime mover, separate operative connections betweenthe power control and the two governors and the displacement control,said operating members being interconnected and mutually interdependentin their total effect upon the power 6. A prime mpver, a pump driventhereby, a-motor driven bythe pump, means for varying the displacementof the pump independent of its rate of rotation and means simultaneouslyresponsive tothe rotational speed of!q the prime mover, the pressure inthe pump and the displacement varying means for v'controlling the poweroutput of the prime mover.

7. The combination with a variable speedA prime mover, a variabledisplacement pump driven thereby, a motor driven by the pump of a mutualcontrol acting upon the prime mover and pump, to simultaneously vary the`displacement of the pump and the power .output of the prime mover.

8.-,'Tl1e combination with a variable speed means comprising anoperative leve.1 di-` rectly connected to the pump and apoweroutput'controlmeans for the prime mover and a connection between it andthe lever.

9. A prlme mover and means for control-A ling its speed, a governorresponsive to the speed of the'prime mover, a Vvariable displacementpump, operating means for varying the displacement of the pump andcoacting means-connected together for operating in unison the operatingmeans, the governor and the speed control. l

10. A prime mover, means for controlling lthe speed thereof, a governoi`responsive to the speed thereof, a variable displacement pump, operatingmeans to vary the displacement thereof, a hydraulic governor responsiveto pressure within the pump and coacting means connecting together theoperating means, the hydraulic governor, the prime mover driven governorand the speed Control means.

11. A prime mover, having a speed governor, a pump driven thereby, amotor driven by the pump, means for controlling the power output of theprime mover, means for selectively adjusting the pump for apredetermined displacement, a hydraulic governor responsive to thepressure in the pump and connections between the power controllingmeans, and the governor and the adjusting means;

12. A prime mover, a pump driven thereby, a motor driven by the pump,means for controlling the power output of the primi?l mover, means forselectively adjusting the pump for apredetermined displacement, ahydraulic -governor operated by the pressure in the pump, an inertiagovernor driven by the prime mover and connections between the powercontrolling means, the adjusting means, the hydraulic governor and theinertia governor. v

13. A by, a motor driven by the pump, means for controlling the poweroutput of the prime mover, means for selectively adjusting the pump fora predetermined displacement, a hydraulic governor responsive to thepressure in the pump and connections between the power controllingmeans, ernor and the adjusting means, said connections beinginterdependent in their action upon the power control means.

14. A prime mover, apump driven thereby, a motor driven by the pump,means for 'controlling the power output of the prime mover, means ,forselectively adjusting the pump for apredetermined displacement, a

and a motor driven by the A prime mover, a pump driven therecontrollingertia governor, said connections being interdependent in their actionupon the powerV control means.

15. A prime mover, a pump driven thereby, a motor` driven by the pump,means for controlling the power output of the prime mover, meansforvarying the displacement of the pump independent of its rate ofrotation, an inertia governor driven by the prime mover, a floatinglever, a connection between it and the power control and connectionsbetween the floating lever and the governor and the pump displacementvarying means.

16. A prime mover, a pump driven thereby, a motor driven by the pump,means for controlling the power output of the prime mover, means forv-arying the displacement of the pump independent of its rate ofrotation, a hydraulic governor responsive to the pressure in the pump, afloating lever, a connection between it and the power control andconnections between the ioating lever and the governor andthe pumpdisplacement-varying means.

17. A prime mover, a pump driven there- IIlOeI', 11163115 means for ofthe pump independent of its rate of rot'a- A tion, a hydraulic governoroperating in response to the pressure in the pump and an inertiagovernor driven by the prime mover, a floating lever, a connectionbetween it and the power control means and separate connections betweenthe ioating lever and the two governors and the pump output varying'means.

18. A prime mover, a variable dlsplacement pump driven thereby, meansfor varydisplacement, a motor driven and'means for controlling the poweroutput of Ithe prime mover simultaneously responsive to the rotationalspeed of the prime mover and to the displacement varying means of thepump.

19. The combination with a prime mover anda power transmission mechanismdriven thereby of means for controlling the power output of the primemover and separate operating means therefor responsive one of them tothe speed of the prime mover, the other to conditions within thetransmission mechanism. p 4

' Signed at South Milwaukee, Wisconsin, this 10th day of J une, 1915.,

WALTER FERRIS. y WlLLlAM E.

ing the pump by the pump,

Witnesses:

W. J. RYAN, E. K/Swlcon'r.

